Our work with adriamycin cardiac toxicity has led us to re-examine the role of endogenous free radical defenses in moderating free radical damage. Since free radical damage is a process which plays a role in such diverse phenomena as aging, ionizing radiation damage, oxygen toxicity, carcinogenesis, and drug toxicity, we have tried to structure our investigation in such a way so as to yield results pertinent to this broad range of problems rather than to focus narrowly on anthracycline cardiac toxicity.